Hong Kong Applied Science and Technology Research Institute Company, Limited

Leung Ling (Alan) Pun

Kwok Kuen (David) Kwong

Chun Fai Wong

Kam Hung Chan

Ho Ming (Karen) Wan

Tat Fu Chan

Guangjie Cai

A differential on-chip temperature sensor circuit can be implemented in a standard complementary metal-oxide-semiconductor (CMOS) process using PNP transistors. A pair of transistors have collector currents that are sensitive to voltage, both directly and due to saturation currents. A scaling resistor connects to the emitter of one transistor and its voltage compared to the other transistor's emitter voltage by an error amplifier that generates a bias voltage to current sources that are proportional to absolute temperature since the saturation current sensitivity is subtracted out. The current is mirrored to sink current through a multiplier resistor from an output. An amplifier connected across the multiplier resistor compares a reference voltage to set the DC bias independent of temperature sensitivity. The temperature sensitivity is proportional to the ratio of the multiplier resistor and the scaling resistor, and is multiplied by a mirroring factor. A differential output is provided.

Differential temperature sensor with sensitivity set by current-mirror and resistor ratios without limiting DC bias

An on-chip temperature sensor circuit can be implemented in a standard complementary metal-oxide-semiconductor (CMOS) process using PNP transistors. A pair of transistors have collector currents that are sensitive to voltage, both directly and due to saturation currents. A scaling resistor connects to the emitter of one transistor and its voltage compared to the other transistor's emitter voltage by an error amplifier that generates a bias voltage to current sources that are proportional to absolute temperature since the saturation current sensitivity is subtracted out. The current is mirrored to sink current through a multiplier resistor from an output. An amplifier connected across the multiplier resistor compares a reference voltage to set the DC bias independent of temperature sensitivity. The temperature sensitivity is proportional to the ratio of the multiplier resistor and the scaling resistor, and is multiplied by a mirroring factor. A differential output may also be provided.

CMOS temperature sensor with sensitivity set by current-mirror and resistor ratios without limiting DC bias

A bridge rectifier operates on low A.C. input voltages such as received by a Radio-Frequency Identification (RFID) device. Voltage drops due to bridge diodes are avoided. Four p-channel transistors are arranged in a transistor bridge across the A.C. inputs to produce an internal power voltage. Another four diode-connected transistors form a start-up diode bridge that generates a comparator power voltage and a reference ground. The start-up diode bridge operates even during initial start-up before the comparator and boost drivers operate. A comparator receives the A.C. input and controls timing of voltage boost drivers that alternately drive gates of the four p-channel transistors in the transistor bridge with voltages boosted higher than the peak A.C. voltage. Substrates are connected to the power voltage on the power-voltage half of the bridge and to the A.C. inputs on the ground half of the bridge to fully shut off transistors, preventing reverse current flow.

Diode-less full-wave rectifier for low-power on-chip AC-DC conversion

An envelope detector receives an input that is an Amplitude-Modulated (AM) or Amplitude-Shift-Keying (ASK) coded signal. Each channel has a sample switch and a diode that charge an internal sampling capacitor. A hold switch connects the internal sampling capacitor to a summing output capacitor or to a post-processing circuit. A reset switch discharges the internal sampling capacitor after each sample. Two or more channels may be time multiplexed to sample alternate cycles of the input, and then their outputs combined by the summing output capacitor or by the post-processing circuit. The diodes may be reversed to detect the negative envelope rather than the positive envelope. Clocks for the switches may be generated from the input, or may be from a separate clock source. Since the sampling window is open for a whole input cycle, the clock source is insensitive to phase error.

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Hong Kong, China

Leung Ling (Alan) Pun