VOLTAGE LEVEL SHIFTER

• US 20090256617A1
• Filed: 04/10/2009
• Published: 10/15/2009
• Est. Priority Date: 04/11/2008
• Status: Active Grant

• Current Assignee: Microsemi Corporation (Microchip Technology Incorporated)
• Original Assignee: Asic Advantage Inc. (Microchip Technology Incorporated)
• Inventors: Ochi, Sam Seiichiro
• Granted Patent: US 7,782,115 B2
• Time in Patent Office: Days
• US Class Current: 327/333
• CPC Class Codes: H03F 2200/291 the level shifting stage between two amplifying stages being realised by a source follower
• CPC Class Codes: H03F 3/2173 of the bridge type
• CPC Class Codes: H03K 17/6874 in a symmetrical configuration
• CPC Class Codes: H03K 19/018564 with at least one differential stage H03K19/018578 takes precedence

Abstract

Methods, systems, and devices are described for providing voltage level shifting that may operate reliably and at low power, even at high voltages and/or high switching frequencies. Embodiments receive an input signal representing input information, and effectively generate two voltage responses as a function of the input signal. Each voltage response includes exponential terms as a function of resistive and capacitive loading effects of components of the embodiments. A combined response signal is generated substantially as a superposition of the first response signal and the second response signal. A high-side driver signal is then generated as a function of the combined response signal, such that the high-side driver signal substantially preserves the input information represented by the input signal, and such that the first exponential response and the second exponential response are substantially absent from the high-side driver signal.

Claims

1. A switching circuit system, comprising:

an input module, operable to receive a two-level input signal representing input information, and to generate a first switching voltage signal and a second switching voltage signal as a function of the input signal;

a current signal generator module, comprising;

a first current switching device, operable to generate a first switching current signal as a function of the first switching voltage signal; and

a second current switching device, operable to generate a second switching current signal as a function of the second switching voltage signal;

a first precharging device, coupled with the first current switching device and the second current switching device, and operable to build up a charge reserve when the second switching voltage signal is HIGH, and to dump at least a portion of the charge reserve into the first current switching device when the first switching voltage signal is HIGH;

a second precharging device, coupled with the first current switching device and the second current switching device, and operable to build up a charge reserve when the first switching voltage signal is HIGH, and to dump at least a portion of the charge reserve into the second current switching device when the second switching voltage signal is HIGH;

a voltage signal generator module, operable to generate a first voltage response as a function of the first switching current signal and to generate a second voltage response as a function of the second switching current signal; and

a latching module, operable to generate a two-level latched signal as a function of the first voltage response and the second voltage response, such that the latched signal substantially preserves the input information represented by the input signal.

2. The circuit switching system of claim 1, wherein the latching module comprises:

a digital latching device, operable to toggle the latched signal from a first logic level to a second logic level when the first voltage response goes HIGH and to toggle the latched signal from the second logic level back to the first logic level when the second voltage response goes HIGH.

3. The circuit switching system of claim 1, wherein the latching module comprises:

a comparator device, operable to;

receive the first voltage response and the second voltage response differentially;

transition the latched signal from a first logic level to a second logic level when the first voltage response exceeds the second voltage response by a first threshold amount; and

transition the latched signal from the second logic level to the first logic level when the second voltage response exceeds the first voltage response by a second threshold amount.

4. The circuit switching system of claim 1, wherein the input module comprises:

an inverter device, configured to invert the input signal, such that the second switching voltage signal is substantially an inverted version of the first switching voltage signal.

5. The circuit switching system of claim 1, wherein the current signal generator module further comprises:

a current source, operable to provide a substantially constant bias current to a source terminal of the first current switching device and a source terminal of the second current switching device;

a first resistive device, coupled with a drain terminal of the first current switching device and a circuit switching node;

a second resistive device, coupled with a drain terminal of the second current switching device and the circuit switching node; and

a third resistive device, coupled between a source voltage level and the circuit switching node,

wherein the input signal has a period, the first current switching device is ON for substantially a first half of the period, and the second current switching device is ON for a second half of the period, such that the bias current flows through the first resistive device and the third resistive device for substantially the first half of the period, and the bias current flows through the second resistive device and the third resistive device for substantially the second half of the period, and

wherein the first voltage response is functionally related to a voltage across the first resistive device and the second voltage response is functionally related to a voltage across the second resistive device.

6. The circuit switching system of claim 1, wherein:

the first precharging device is a first capacitive device having;

a first terminal coupled with a gate terminal of the first current switching device; and

a second terminal coupled with a drain terminal of the second current switching device and a first input terminal of the latching module; and

the second precharging device is a second capacitive device having;

a first terminal coupled with a gate terminal of the second current switching device; and

a second terminal coupled with a drain terminal of the first current switching device and a second input terminal of the latching module.

7. The circuit switching system of claim 6, further comprising:

a third capacitive device coupled between a source voltage level and the second terminal of the first capacitive device; and

a fourth capacitive device coupled between the source voltage level and the second terminal of the second capacitive device.

8. The circuit switching system of claim 1, further comprising:

a high-side switching device, coupled between a source voltage level and an output voltage level, and configured to be switched as a function of the latched signal and to pull the output voltage level substantially to the source voltage level when the high-side switching device is ON.

9. The circuit switching system of claim 8, further comprising:

a driver module, communicatively coupled with the latching module, and operable to generate a driver signal as a function of the latched signal, the driver signal being configured to switch the high-side switching device,

wherein the high-side switching device is configured to be switched as a function of the driver signal.

10. The circuit switching system of claim 8, further comprising:

a low-side switching device, coupled between the output voltage level and a ground level, and configured to be switched as a function of a low-side driver signal and to pull the output voltage level substantially to the ground voltage level when the low-side switching device is ON.

11. The circuit switching system of claim 10, further comprising:

a low-side driver module, operable to receive a low-side input signal and generate the low-side driver signal as a function of the low-side input signal.

12. The circuit switching system of claim 11,

wherein the low-side driver module is operable to generate the low-side driver signal, such that the low-side switching device is switched ON only when the high-side switching device is OFF.

13. The circuit switching system of claim 10, wherein:

the high-side switching device and the low-side switching device are configured in a half-bridge topology.

14. The circuit switching system of claim 1, further comprising:

a packaging, configured to house at least the input module, the current signal generator module, first precharging device, the second precharging device, and the voltage signal generator module, the packaging comprising at least one interface terminal configured to communicatively couple the input module with a source of the input signal located external to the packaging.

20. The circuit switching system of claim 1, further comprising:

means for housing at least the means for receiving a two-level input signal, the means for generating a first response signal, the means for generating a second response signal, and the means for generating a combined response,

wherein the means for housing comprises a means for providing a communicatively coupling between the first means and a source of the input signal located external to the means for housing.

15. A switching circuit system, comprising:

means for receiving a two-level input signal representing input information;

means for generating a first response signal as a function of the input signal, the first response signal comprising a first exponential response defined substantially as a voltage across a first network in response to a switched current applied to the first network, the first network consisting of a first resistive load coupled in parallel with a first capacitive load;

means for generating a second response signal as a function of the input signal, the second response signal comprising a second exponential response defined substantially as a voltage across a second network in response to a switched voltage applied across a third network, the second network consisting of a second resistive load coupled in parallel with a second capacitive load, and the third network consisting of a third capacitive load coupled in series with the second network;

means for generating a combined response signal being substantially a superposition of the first response signal and the second response signal; and

means for generating a high-side driver signal as a function of the combined response signal, such that the high-side driver signal substantially preserves the input information represented by the input signal, and such that the first exponential response and the second exponential response are substantially absent from the high-side driver signal.

16. The circuit switching system of claim 15, wherein:

the first resistive load is equivalent to the second resistive load; and

the first capacitive load is equivalent to the second capacitive load.

17. The circuit switching system of claim 15, wherein:

the means for generating a combined response is configured to generate the combined response signal by isolating the first exponential response and the second exponential response substantially to a common mode of the combined response signal; and

the means for generating a high-side driver signal is configured to generate the high-side driver signal by rejecting the common mode of the combined response signal, such that the first exponential response and the second exponential response are substantially absent from the high-side driver signal.

18. The circuit switching system of claim 15, further comprising:

means for switching an output level to a source voltage level as a function of the high-side driver signal.

19. The circuit switching system of claim 18, further comprising:

means for generating a low-side driver signal configured to be HIGH only when the high-side driver signal is LOW; and

means for switching the output level to a ground level as a function of the low-side driver signal.

21. A method for voltage level shifting, comprising:

receiving a two-level input signal representing input information;

generating a first response signal as a function of the input signal, the first response signal comprising a first exponential response defined substantially as a voltage across a first network in response to a switched current applied to the first network, the first network consisting of a resistive load coupled in parallel with a first capacitive load;

generating a second response signal as a function of the input signal, the second response signal comprising a second exponential response defined substantially as a voltage across the first network in response to a switched voltage applied across a second network, the second network consisting of a second capacitive load coupled in series with the first network;

generating a combined response signal being substantially a superposition of the first response signal and the second response signal; and

generating a high-side driver signal as a function of the combined response signal, such that the high-side driver signal substantially preserves the input information represented by the input signal, and such that the first exponential response and the second exponential response are substantially absent from the high-side driver signal.

22. The method of claim 21, wherein:

generating the first response signal as a function of the input signal comprises;

generating a first switching voltage signal and a second switching voltage signal as a function of the input signal;

generating a first switching current signal as a function of the first switching voltage signal; and

generating a second switching current signal as a function of the second switching voltage signal; and

generating the second response signal as a function of the input signal comprises;

when the second switching voltage signal is HIGH, building up a first charge reserve on a first precharging device and dumping at least a portion of a second charge reserve into the second current switching device; and

when the first switching voltage signal is HIGH, building up the second charge reserve on a second precharging device and dumping at least a portion of the first charge reserve into the first current switching device.

23. The method of claim 21, wherein:

generating the combined response signal comprises;

receiving the first response signal and the second response signal differentially; and

isolating the first exponential response and the second exponential response substantially to a common mode of the combined response signal; and

generating the high-side driver signal as a function of the combined response signal comprises rejecting the common mode of the combined response signal, such that the first exponential response and the second exponential response are substantially absent from the high-side driver signal.

24. The method of claim 21, wherein:

the combined response signal is defined substantially by the equation;