Datasheet AD8372 (Analog Devices)

41 dB Range, 1 dB Step Size, Programmable Dual VGA Data Sheet AD8372 FEATURES FUNCTIONAL BLOCK DIAGRAM Dual independent digitally controlled VGA ENB1 REF1 AD8372 Differential input and output IPC1 OPC1 150 Ω differential input INC1 ONC1 Open-collector differential output CHANNEL 1 POSTAMP RXT1 7.8 dB noise figure to 100 MHz @ maximum gain HD2/HD3 better than 77 dBc for 1 V p-p differential output CLK1 CLK2 SDO1 REGISTERS SDO2 −3 dB bandwidth of 130 MHz AND SDI1 GAIN DECODER SDI2 41 dB gain range LCH1 LCH2 1 dB step size ± 0.2 dB RXT2 Serial 8-bit bidirectional SPI control interface IPC2 OPC2 Wide input dynamic range INC2 ONC2
01 0
Pin-programmable output stage ENB2 CHANNEL 2 POSTAMP
1-
REF2
05 07
Power-down feature
Figure 1.
Single 5 V supply: 106 mA per channel 32-lead LFCSP, 5 mm × 5 mm package APPLICATIONS Differential ADC drivers CMTS upstream direct sampling receivers CATV modem signal scaling Generic RF/IF gain stages Single-ended-to-differential conversion GENERAL DESCRIPTION
The AD8372 is a dual, digitally controlled, variable gain setting resistors can be adjusted to manipulate the gain and amplifier (VGA) that provides precise gain control, high IP3, distortion performance of each channel. This is a flexible and low noise figure. The excellent distortion performance and feature in applications where it is desirable to trade off distortion moderate signal bandwidth make the AD8372 a suitable performance for lower power consumption. gain control device for a variety of multichannel receiver The AD8372 is powered on by applying the appropriate logic applications. level to the ENB1, ENB2 pins. When powered down, the AD8372 For wide input dynamic range applications, the AD8372 consumes less than 2.6 mA and offers excellent input-to-output provides a broad 41 dB gain range. The gain is programmed isolation. The gain setting is preserved when powered down. through a bidirectional 4-pin serial interface. The serial inter- Fabricated on an Analog Devices, Inc., high frequency BiCMOS face consists of a clock, latch, data input, and data output lines process, the AD8372 provides precise gain adjustment capabilities for each channel. with good distortion performance. The quiescent current of the The AD8372 provides the ability to set the transconductance of AD8372 is typically 106 mA per channel. The AD8372 amplifier the output stage using a single external resistor. The RXT1 and comes in a compact, thermally enhanced 5 mm × 5 mm 32-lead RXT2 pins provide a band gap derived stable reference voltage LFCSP package and operates over the temperature range of of 1.56 V. Typically 2.0 kΩ shunt resistors to ground are used to −40°C to +85°C. set the maximum gain to a nominal value of 31 dB. The current
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Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION REVISION HISTORY SPECIFICATIONS SERIAL CONTROL INTERFACE TIMING ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION SINGLE-ENDED AND DIFFERENTIAL SIGNALS PASSIVE FILTER TECHNIQUES DIGITAL GAIN CONTROL DRIVING ANALOG-TO-DIGITAL CONVERTERS EVALUATION BOARD SCHEMATIC OUTLINE DIMENSIONS ORDERING GUIDE