Power detector using a constant quiescent voltage divider
AssigneesSharp Microelectronics Technology, Inc., Sharp Kabushiki Kaisha
InventorsDouglas James Millar, Tai Won Youn, Chen Zhang
Life of this patent
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Abstract
A control circuit which regulates an ac power output device. The control circuit is operatively connected to the ac power output and measures the ac signal with a diode to generate a control signal stimulus. A second diode is operatively connected to the power measuring diode so that the two diodes have the same voltage drops associated with the quiescent operation of the diodes. Quiescent voltage changes in the power measuring diode are canceled by the matching quiescent voltage change in the second diode. In this manner, power measurement errors associated with diode quiescent voltage changes are minimized.
Claims25
A control circuit and an ac power output device, said control circuit providing an ac power level control signal to regulate the power level of said ac power output device, and said control circuit comprising:
- a) a first diode, operatively connected to the ac power output device, which outputs a first control signal having a quiescent signal component and a signal component which varies in response to the ac power;
- b) a second diode operatively connected to said first diode which outputs a second control signal having a quiescent signal component matching the quiescent signal component of the first control signal to maintain the quiescent voltage of the first signal within a predetermined range;
- and
- c) a detected voltage node between said first and second diodes to provide the first control signal, from which the ac power level control signal is derived, whereby power measurement errors due to temperature changes are minimized.
A control circuit and an ac power output device, said control circuit providing an ac power level control signal to regulate the power level of said ac power output device, said control circuit comprising:
- a) a quiescent voltage source and a quiescent reference voltage;
- b) a first diode having two terminals, said first diode first terminal being an anode operatively connected to the quiescent voltage source, and said first diode second terminal being a cathode, said first diode operatively connected to the ac power output device to output a first control signal having a quiescent signal component and a signal component which varies in response to the ac power, the ac power level control signal being derived from the first control signal;
- c) a second diode having two terminals, said second diode first terminal being an anode operatively connected in series to said first diode second terminal to output a second control signal having a quiescent signal component matching the quiescent signal component of the first control signal, and said second diode second terminal being a cathode operatively connected to the quiescent voltage reference, whereby said diodes are operatively connected in series between said quiescent voltage source and said quiescent reference voltage;
- d) a first resistive element, having two terminals, operatively connecting said anode of said first diode to the quiescent voltage source;
- and
- e) a second resistive element, having two terminals, operatively connecting said cathode of said first diode to said anode of said second diode.
A control circuit for maintaining the output level of an ac power output device within a predetermined range with an ac power level control signal, said control circuit comprising:
- a) sampling means operatively connected to said ac power device for sampling a portion of the ac power output to provide a sampled ac power signal;
- b) first control signal means operatively connected to said sampling means for producing a first control signal having a quiescent signal component and a signal component responsive to the sampled ac power signal, the ac power level control signal being derived from the first control signal;
- and
- c) second control signal means operatively connected to said first control signal means for producing a second control signal having a quiescent signal component matching the quiescent signal component of the first control signal, whereby the matching of quiescent signal components allows the first control signal quiescent component to remain within a predetermined range over a varying operating temperature.
Dependencies are inferred from the claim text.