Low power transmitter oscillator circuits and methods

Patent metadata

Field	Value
Publication number	US-10897240-B2
Application number	US-201916961471-A
Country	US
Kind code	B2
Filing date	Jan 15, 2019
Priority date	Jan 15, 2018
Publication date	Jan 19, 2021
Grant date	Jan 19, 2021

Abstract

A fast startup power oscillator transmitter includes a transistor pair that drives a resonant circuit including a tunable capacitance. A capacitor array preferably forms the tunable capacitance. A voltage booster activates the capacitor array. A clamped body bias voltage booster can set the body bias voltage of the transistor pair in one circuit. Control circuitry activates the resonant circuit through a triode-mode switch transistor in response to an input in a range of 0.3-0.6V, and preferably while controlling the substrate bias voltage of the transistor pair to increase transconductance of the cross-coupled transistor pair. In a variation, a circuit pushes a top plate voltage of one of the two capacitors to 2VDD and pulls the top plate voltage of the other to zero to give the oscillator an initial condition. In a variation, a shaped pulse drives the transistor pair to switch to a class D oscillator mode, and the triode mode switch transistor is only turned on when the oscillation signal voltage is in the range of 0.3-0.6V.

First claim

The invention claimed is:

1. A fast startup power oscillator transmitter comprising:
a transistor pair that drives a resonant circuit including a tunable capacitance;
a voltage booster that activates the capacitance;
and control circuitry to activate the resonant circuit through a triode-mode switch transistor driven in response to an input in a range of 0.3-0.6V.

2. The transmitter of claim 1 , wherein the transistor pair comprises a cross-coupled transistor pair.

3. The transmitter of claim 2 , wherein the capacitance includes a capacitor array that comprises:
two switch-mode transistors and two capacitors, the control circuitry switching bottom plates of the two capacitors between a the power supply voltage V DD and ground, wherein during an initial condition, one of switch-mode transistors connects a bottom plate of a respective one of the two capacitors to GND and the other one of the two capacitors is switched to V DD , and then bottom plate connections are switched to during a start phase to push a top plate voltage of one of the two capacitors to 2V DD and pull the top plate voltage of the other to zero to give the oscillator an initial condition.

4. The transmitter of claim 1 , wherein the control circuitry comprises a level shifter that shifts average voltage of an output signal to half V DD ;
an amplifier that amplifies the output signal of the level shifter to full swing;
an inverter that rectify the full swing sinusoidal signal to a square signal;
a pulse generator that shape the square wave and control the duty cycle of the square signal.

5. The transmitter of claim 1 , connected to an impedance matched antenna.

6. The transmitter of claim 1 , wherein the control circuit comprises a plurality of amplifiers, wherein the output of one amplifier of the plurality is rectified and pulse-shaped, then drives the gate of another one amplifier of the plurality.

7. The transmitter of claim 1 , wherein the control circuitry controls the tunable capacitance to provide an initial condition of a voltage difference at least 1.5 times a supply voltage across an antenna driven by the oscillator.

8. The transmitter of claim 7 , wherein the voltage difference is 1.8 to 2.2 times the supply voltage.

9. The transmitter of claim 1 , wherein the triode-mode switch transistor controls ON and OFF states of the transmitter.

10. The transmitter of claim 9 , wherein the control circuitry reduces ON resistance of the transistor pair.

11. The transmitter of claim 1 , wherein the capacitance comprises a capacitor array with a plurality of capacitor layers, each layer including a set of frequency tuning capacitors.

12. The transmitter of claim 1 , wherein a shaped pulse drives the transistor pair to switch to a class D oscillator mode, and the triode mode switch transistor is only turned on when the oscillation signal voltage is in the range of 0.3-0.6V.

13. The transmitter of claim 1 , wherein the capacitance comprises a capacitor array.

14. The transmitter of claim 1 , further comprising a clamped body bias voltage booster to set the body bias voltage of the transistor pair, wherein the control circuitry controls the substrate bias voltage of the transistor pair to increase transconductance of the transistor pair.

15. The transmitter of claim 1 , integrated on-chip in CMOS.

16. The transmitter of claim 15 , wherein the transmitter consumes an average power of no more than ˜1.15 μW.

Assignees

• Univ California

Inventors

• Wang Xiaoyang
• Mercier Patrick

Classifications

• H03K3/03 Primary

  Astable circuits · CPC title

• H03K3/0231

  Astable circuits {(H03K3/0315 takes precedence)} · CPC title

• H03K17/0812

  by measures taken in the control circuit · CPC title

• H03K3/014

  Modifications of generator to ensure starting of oscillations · CPC title

• H03K17/687

  the devices being field-effect transistors · CPC title