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Datasheet Analog Devices AD8338ACPZ-RL

Analog Devices AD8338ACPZ-RL

Manufacturer:Analog Devices
Series:AD8338
Part Number:AD8338ACPZ-RL

Low Power, 18 MHz Variable Gain Amplifier

Datasheets

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    Data Sheet
    FEATURES Low Power, 18 MHz Variable Gain Amplifier AD8338
    FUNCTIONAL BLOCK DIAGRAM
    VBAT OFSN VREF OFFSET NULL Voltage controlled gain range of 0 dB to 80 dB 3 mA supply current at gain of 40 dB Low frequency (LF) to 18 MHz operation Supply range: 3.0 V to 5.0 V Low noise: 4.5 nV/Hz at 80 dB gain Fully differential signal path Offset correction (offset null) feature Internal 1.5 V reference 16-lead LFCSP Automatic gain control feature Wide gain range for high dynamic range signals AD8338 FBKP VGA CORE INPR + + OUTPUT STAGE 0dB ­ 0dB TO 80dB INPD VREF FBKM OUTP INMR ­ OUTM INMD GAIN INTERFACE Front end for inductive telemetry systems Ultrasonic signal receivers Signal compression for driving an ADC AGC amplifiers COMM MODE GAIN DETO VAGC Figure 1.
    100 80 60
    VGAIN = 1.1V VGAIN = 1.0V VGAIN = 0.9V VGAIN = 0.8V VGAIN = 0.7V VGAIN = 0.6V VGAIN = 0.5V VGAIN = 0.4V VGAIN = 0.3V VGAIN = 0.2V VGAIN = 0.1V GENERAL DESCRIPTION
    The AD8338 is a variable gain amplifier (VGA) for applications that require a fully differential signal path, low power, low noise, and a well-defined gain over frequency. While the inputs are differential, the device can also be driven with a single-ended source if required. The basic gain function is linear-in-dB and is controlled by the voltage applied to Pin GAIN. The nominal gain range spans from 0 dB to 80 dB for control voltages between 0.1 V to 1.1 V with a slope of 12.5 mV/dB. The nominal gain range can be shifted up or down via direct access to Pin INPD and Pin INMD, the current inputs of the VGA. For example, driving the INPD and INMD pins with 50 resistors shifts the gain range up by 20 dB, that is, 20 dB to 100 dB, and lowers the input referred noise of the device to 1.5 nV/Hz. Additionally, the gain slope can be inverted via logic Pin MODE. The AD8338 includes additional circuit blocks to enable input offset correction and automatic gain control (AGC). DC offset voltages are removed by the offset correction circuit, which behaves like a high-pass filter whose corner is set with an external capacitor. The AGC function varies the gain of the AD8338 to maintain a constant RMS output voltage. An externally applied voltage to Pin VAGC with respect to the voltage at Pin VREF sets the output RMS amplitude. A capacitor from Pin DETO to ground sets the response time of the AGC circuit. GAIN (dB) 40 20 0 ­20 ­40 10k 100k 1M FREQUENCY (Hz) 10M 100M Figure 2. Gain vs. Frequency The AD8338 offers additional versatility by providing access to the internal summing nodes of the VGA core and the output amplifiers. With the addition of ...

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Other Names: AD8338ACPZRL, AD8338ACPZ RL

Docket:
Data Sheet
FEATURES Low Power, 18 MHz Variable Gain Amplifier AD8338
FUNCTIONAL BLOCK DIAGRAM
VBAT OFSN VREF OFFSET NULL Voltage controlled gain range of 0 dB to 80 dB 3 mA supply current at gain of 40 dB Low frequency (LF) to 18 MHz operation Supply range: 3.0 V to 5.0 V Low noise: 4.5 nV/Hz at 80 dB gain Fully differential signal path Offset correction (offset null) feature Internal 1.5 V reference 16-lead LFCSP Automatic gain control feature Wide gain range for high dynamic range signals AD8338 FBKP VGA CORE INPR + + OUTPUT STAGE 0dB ­ 0dB TO 80dB INPD VREF FBKM OUTP INMR ­ OUTM INMD GAIN INTERFACE Front end for inductive telemetry systems Ultrasonic signal receivers Signal compression for driving an ADC AGC amplifiers COMM MODE GAIN DETO VAGC Figure 1.
100 80 60
VGAIN = 1.1V VGAIN = 1.0V VGAIN = 0.9V VGAIN = 0.8V VGAIN = 0.7V VGAIN = 0.6V VGAIN = 0.5V VGAIN = 0.4V VGAIN = 0.3V VGAIN = 0.2V VGAIN = 0.1V GENERAL DESCRIPTION
The AD8338 is a variable gain amplifier (VGA) for applications that require a fully differential signal path, low power, low noise, and a well-defined gain over frequency. While the inputs are differential, the device can also be driven with a single-ended source if required. The basic gain function is linear-in-dB and is controlled by the voltage applied to Pin GAIN. The nominal gain range spans from 0 dB to 80 dB for control voltages between 0.1 V to 1.1 V with a slope of 12.5 mV/dB. The nominal gain range can be shifted up or down via direct access to Pin INPD and Pin INMD, the current inputs of the VGA. For...

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