Search

US-20260128714-A1 - MULTI-MODE VOLTAGE-CONTROLLED OSCILLATOR (VCO) WITH TRANSFORMER-BASED COUPLING

US20260128714A1US 20260128714 A1US20260128714 A1US 20260128714A1US-20260128714-A1

Abstract

Techniques and apparatus for oscillating signal generation using a multi-mode voltage-controlled oscillator (VCO) circuit with transformer-based coupling. An example VCO circuit generally includes a first pair of transistors associated with a first active negative transconductance circuit; a second pair of transistors associated with a second active negative transconductance circuit; a transformer comprising a primary winding and a secondary winding, the primary winding being coupled to the second pair of transistors; a first set of switches coupled between gates of the first pair of transistors and the secondary winding of the transformer; and a second set of switches coupled between the gates of the first pair of transistors and a first voltage node.

Inventors

  • Shilei Hao
  • Yiwu Tang

Assignees

  • QUALCOMM INCORPORATED

Dates

Publication Date
20260507
Application Date
20241106

Claims (20)

  1. 1 . A voltage-controlled oscillator (VCO) circuit comprising: a first pair of transistors for a first active negative transconductance circuit; a second pair of transistors for a second active negative transconductance circuit; a transformer comprising a primary winding and a secondary winding, the primary winding being coupled between drains of the second pair of transistors; a first set of switches coupled between gates of the first pair of transistors and the secondary winding of the transformer; and a second set of switches coupled between the gates of the first pair of transistors and a first voltage node.
  2. 2 . The VCO circuit of claim 1 , further comprising a switch including a first terminal coupled to a tap of the primary winding and including a second terminal coupled to a second voltage node.
  3. 3 . The VCO circuit of claim 2 , wherein in a first mode: the first set of switches are configured to be open; the second set of switches are configured to be closed; and the switch is configured to be closed to couple the tap of the primary winding to the second voltage node.
  4. 4 . The VCO circuit of claim 3 , wherein in the first mode, the first active negative transconductance circuit is disabled and the second pair of transistors are effectively cross-coupled in the second active negative transconductance circuit.
  5. 5 . The VCO circuit of claim 3 , wherein in a second mode: the first set of switches are configured to be closed; the second set of switches are configured to be open; and the switch is configured to be open.
  6. 6 . The VCO circuit of claim 2 , further comprising: a third set of switches coupled between gates of the second pair of transistors and the secondary winding of the transformer; and a fourth set of switches coupled between the gates of the second pair of transistors and a third voltage node, wherein the switch further includes a third terminal coupled to a fourth voltage node and wherein the switch can be configured to at least one of: be open, couple the first terminal to the second terminal, or couple the first terminal to the third terminal.
  7. 7 . The VCO circuit of claim 6 , wherein in a first mode: the first set of switches are configured to be open; the second set of switches are configured to be closed; the switch is configured to couple the tap of the primary winding to the second voltage node; the third set of switches are configured to be closed; the fourth set of switches are configured to be open; and the first active negative transconductance circuit is disabled.
  8. 8 . The VCO circuit of claim 7 , wherein in a second mode: the first set of switches are configured to be closed; the second set of switches are configured to be open; the switch is configured to couple the tap of the primary winding to the fourth voltage node; the third set of switches are configured to be open; the fourth set of switches are configured to be closed; and the second active negative transconductance circuit is disabled.
  9. 9 . The VCO circuit of claim 8 , wherein in a third mode: the first set of switches are configured to be closed; the second set of switches are configured to be open; the switch is configured to be open; the third set of switches are configured to be closed; and the fourth set of switches are configured to be open.
  10. 10 . The VCO circuit of claim 8 , wherein the second voltage node comprises a power supply rail for the VCO circuit and wherein the fourth voltage node comprises a reference potential node for the VCO circuit.
  11. 11 . The VCO circuit of claim 1 , wherein the first active negative transconductance circuit comprises a plurality of controllable active negative transconductance cells and wherein one of the controllable active negative transconductance cells comprises the first pair of transistors, the first set of switches, and the second set of switches.
  12. 12 . The VCO circuit of claim 1 , wherein the VCO circuit lacks an alternating current (AC) coupling capacitor coupled between transistors in the first pair of transistors.
  13. 13 . The VCO circuit of claim 1 , wherein the gates of the first pair of transistors are directly connected to the secondary winding via respective switches of the first set of switches.
  14. 14 . The VCO circuit of claim 1 , further comprising a third set of switches, wherein the transformer further comprises a tertiary winding and wherein the third set of switches are coupled between gates of the second pair of transistors and the tertiary winding of the transformer.
  15. 15 . The VCO circuit of claim 14 , wherein the secondary winding and the tertiary winding have different coupling coefficients.
  16. 16 . The VCO circuit of claim 1 , wherein the primary winding is coupled to drains of the first pair of transistors and to the drains of the second pair of transistors.
  17. 17 . A method of oscillating signal generation using a voltage-controlled oscillator (VCO) circuit, the method comprising: controlling a first set of switches coupled between gates of a first pair of transistors for a first active negative transconductance circuit and a secondary winding of a transformer; and controlling a second set of switches coupled between the gates of the first pair of transistors and a first voltage node, wherein a primary winding of the transformer is coupled between drains of a second pair of transistors for a second active negative transconductance circuit.
  18. 18 . The method of claim 17 , further comprising controlling a switch including a first terminal coupled to a tap of the primary winding and including a second terminal coupled to a second voltage node.
  19. 19 . The method of claim 18 , wherein in a first mode: controlling the first set of switches comprises opening the first set of switches; controlling the second set of switches comprises closing the second set of switches; and controlling the switch comprises closing the switch to couple the tap of the primary winding to the second voltage node, such that the first active negative transconductance circuit is disabled and the second pair of transistors are effectively cross-coupled in the second active negative transconductance circuit.
  20. 20 . The method of claim 19 , wherein in a second mode: controlling the first set of switches comprises closing the first set of switches; controlling the second set of switches comprises opening the second set of switches; and controlling the switch comprises opening the switch.

Description

TECHNICAL FIELD Certain aspects of the present disclosure generally relate to electronic circuits and, more particularly, to voltage-controlled oscillators (VCOs) with transformer-based coupling. BACKGROUND Wireless communication devices are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such wireless communication devices may transmit and/or receive radio frequency (RF) signals via any of various suitable radio access technologies (RATs) including, but not limited to, 5G New Radio (NR), Long Term Evolution (LTE), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Wideband CDMA (WCDMA), Global System for Mobility (GSM), Bluetooth, Bluetooth Low Energy (BLE), ZigBee, wireless local area network (WLAN) RATs (e.g., WiFi), and the like. A wireless communication network may include a number of base stations that can support communication for a number of mobile stations. A mobile station (MS) may communicate with a base station (BS) via a downlink and an uplink. The downlink (or forward link) refers to the communication link from the base station to the mobile station, and the uplink (or reverse link) refers to the communication link from the mobile station to the base station. A base station may transmit data and control information on the downlink to a mobile station and/or may receive data and control information on the uplink from the mobile station. The base station and/or mobile station may include at least one phase-locked loop (PLL), which may be used, for example, in a frequency synthesizer to generate and control a local oscillator (LO) signal for mixing with a baseband signal (or a radio frequency (RF) signal) for upconversion (or downconversion) to an intermediate frequency (IF) signal or an RF signal (or an IF signal or a baseband signal) before transmission (after reception). The frequency synthesizer may include a voltage-controlled oscillator (VCO) for tuning an oscillating signal to different frequencies. SUMMARY The systems, methods, and devices of the disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this disclosure as expressed by the claims which follow, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description,” one will understand how the features of this disclosure provide the advantages described herein. Certain aspects of the present disclosure generally relate to oscillating signal generation using a multi-mode voltage-controlled oscillator (VCO) circuit with transformer-based coupling. Certain aspects of present disclosure are directed to a VCO circuit. The VCO circuit generally includes a first pair of transistors associated with a first active negative transconductance circuit; a second pair of transistors associated with a second active negative transconductance circuit; a transformer comprising a primary winding and a secondary winding, the primary winding being coupled to the second pair of transistors; a first set of switches coupled between gates of the first pair of transistors and the secondary winding of the transformer; and a second set of switches coupled between the gates of the first pair of transistors and a first voltage node. The first pair of transistors may be configured to selectively implement the first active negative transconductance circuit, and the second pair of transistors may be configured to selectively implement the second active negative transconductance circuit. Certain aspects of the present disclosure are directed to a method of oscillating signal generation using a VCO circuit. The method generally includes controlling a first set of switches coupled between gates of a first pair of transistors for a first active negative transconductance circuit and a secondary winding of a transformer; and controlling a second set of switches coupled between the gates of the first pair of transistors and a first voltage node, wherein a primary winding of the transformer is coupled to a second pair of transistors for a second active negative transconductance circuit. To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be