A low noise single-end to differential switched-capacitor VGA for PZT-Xducer ultrasound imaging

Analog Integr Circ Sig Process

2015

This paper presents two inverter-based lownoise, low-power, single-ended to differential switchedcapacitor variable gain amplifiers (SC-VGAs) for 2-6-MHz second harmonic cardiac ultrasound imaging probes fabricated with 0.18 lm complementary metal-oxidesemiconductor technology. By employing inverters in class C mode instead of operational trans-conductance amplifiers, the power consumption of 150 lW at a supply voltage of 1 V is achieved for both VGAs; -75 and -72 dBm of integrated noise with 2-6-MHz bandwidth at maximum gain and a sampling frequency of 30 MHz are achieved for VGA1 and VGA2, respectively. Both VGAs have two stages. VGA1 uses a fully switched-capacitor approach for gain control, and the gain range is -21-21 dB with 12-bit capacitor arrays. VGA2 adopts an inverter-based SC-VGA in the first stage with a 6-bit capacitor array to tune the gain from -9 to 9 dB, and the second stage is a differential amplifier with a 4-bit thermometer-coded resistor array to tune the gain from 0 to 13 dB. Both SC-VGAs complete the single-ended to differential conversion in the second stage to suppress the second harmonic distortion (HD2). Both VGAs have HD2 less than -50 dB. The die size of VGA1 is 245 lm 9 134 lm, and the die size of VGA2 is 109 lm 9 164 lm.

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Section: Vga1supporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Inverter-based low-noise, 150 µW single-ended to differential SC-VGAs for second harmonic cardiac ultrasound imaging probes

Analog Integr Circ Sig Process

2015

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“…This work introduces a low‐noise single‐ended to differential two‐stage 10‐bit SC‐VGA for 2–6 MHz second harmonic cardiac medical ultrasound imaging systems [12]. The designed HD2 and third harmonic distortion (HD3) are <−50 dB, the gain is >20 dB to suppress the noise from the following stages.…”

Section: Introductionmentioning

confidence: 99%

Low noise, −50 dB second harmonic distortion single‐ended to differential switched‐capacitive variable gain amplifier for ultrasound imaging

IET Circuits, Devices & Systems

2016

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A low noise, low power, single-ended to differential switched-capacitor variable gain amplifier (SC-VGA) is designed and fabricated in 0.18 µm complementary metal-oxide-semiconductor technology for a 2-6 MHz second harmonic cardiac ultrasound imaging system. The SC-VGA has 10-bit dB-linear gain steps from −14 to 32 dB which are distributed into two stages, and each stage has a single-stage operational trans-conductance amplifier using floating capacitors to save the power and improve the noise performance. The first stage converts the single-ended input to differential outputs with the 2-bit gain control from 0 to 18 dB, and the second stage exploits 8-bit capacitor arrays to control the gain from −14 to 14 dB. The measured results show that the second harmonic distortion is <−50 dB, the third harmonic distortion is <−50 dB and the integrated noise from 2 to 6 MHz at the output is −64 dBm at the maximum gain and a sampling frequency of 30 MHz. The simulation results match well with the measured results. The SC-VGA works at a supply voltage of 1.6 V and consumes the current of 900 µA. The die size of the SC-VGA is 387 µm × 502 µm.

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Surfing front-end architectures for ultrasound imaging systems

2015 European Conference on Circuit Theory and Design (ECCTD)

Halvorsrod³

2015