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Programmable Gain Amplifier

Takashi Yamaguchi
Genius 14100 points

Other Parts Discussed in Thread: PGA2505, PGA4311, PGA2500, PGA103, PGA112, PGA113, PGA116, PGA117, PGA202, PGA203, PGA204, PGA205, PGA206, PGA207, PGA280, PGA281, VCA810, VCA2612, VCA822, VCA820

Hi team,

Do you have a programmable gain amp (PGA) or AD converter that can change the gain in an analog (continuous) manner?
I could only find the ones that set the discrete values such as 1,2,4,8 ~ 256,512.
For example, from 1 to 1000, it would be nice to have something that can be done in 1 or 10 increments.

Regards,

Yamaguchi

  • 0
    TI__Guru 55466 points

    HI Takashi,

    As you have mentioned, the Programmable Gain Amplifiers on the precision amplifiers portfolio offer gains in binary, decade or scope increments.

    Decade Gains: 1, 10, 100...

    Binary Gains: 1, 2, 4, 8, 16...

    Scope gains: 1, 2, 5, 10, 20, 50, 100, 200

    Beyond these, there are Audio PGA Audio volume control devices such as the PGA4311, PGA2500/PGA2505 that have gain increments in ~0.5 dB (or 3dB steps).

    Unfortunately, there are no PGAs with 1V/V or 10 V/V increment steps. 

     Please find below a table with Precision PGA devices.

    Thank you and Regards,

    Luis

    Table 1: Single-Ended to Single-Ended

    Part

    Supply

    Channels

    Gain (dB)

    Number of

    Gain Scale

    Interface

    Number

    Min (V)

    Min

    Gains

     

    Max (V)

    Max

     

    PGA103

    9

    1

    0

    3

    Decade

    Parallel

    36

    40

    PGA112

    2.2

    2

    0

    8

    Binary

    SPI

    5.5

    42

    PGA113

    2.2

    2

    0

    8

    Scope

    SPI

    5.5

    42

    PGA116

    2.2

    10

    0

    8

    Binary

    SPI

    5.5

    46

    PGA117

    2.2

    10

    0

    8

    Scope

    SPI

    5.5

    46

    Table 2: Differential to Single-Ended

    Part

    Supply

    Channels

    Gain (dB)

    Number of

    Gain Scale

    Interface

    Number

    Min (V)

    Min

    Gains

     

    Max (V)

    Max

     

    PGA202

    12

    1

    0

    4

    Decade

    Parallel

    36

    60

    PGA203

    12

    1

    0

    4

    Binary

    Parallel

    36

    18

    PGA204

    9

    1

    0

    4

    Decade

    Parallel

    36

    60

    PGA205

    9

    1

    0

    4

    Binary

    Parallel

    36

    18

    PGA206

    9

    1

    0

    4

    Binary

    Parallel

    36

    18

    PGA207

    9

    1

    0

    4

    Decade

    Parallel

    36

    20

    Table 3: Differential to Differential

    Part

    Supply

    Channels

    Gain (dB)

    Number of

    Gain Scale

    Interface

    Number

    Min (V)

    Min

    Gains

     

    Max (V)

    Max

     

    PGA280

    10

    2

    -18

    11

    Binary

    SPI

    36

    42

    PGA281

    10

    1

    -18

    11

    Binary

    Parallel

    36

    42
  • 0
    TI__Guru* 93105 points

    Yamaguchi-san,

    None of TI Precision Amplifiers PGAs can be stepped from gains of 1x to 1000x, in G = 1 or 10 V/V steps. The internal resistor combinations required to do the G = 1 or 10 V/V increments through a gain of 1000x, would require a massive amount of resistor die area and resistor trimming making it impractical to to manufacture.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • 0
    Guru 48395 points

    Hello Takashi-san

    There are a few continuous time VCA's that take an analog control voltage, you could consider the (none of these are particularly good DC precision)

    VCA810 (lower speed, very poor harmonic distortion, but good for time domain)

    And then there are a string of multichannel parts for ultrasound like the VCA2612 - better noise - but also digital gain control

    And then there are very fast parts like these that have an analog control input - the 1st is dB/V adjust, the 2nd is V/V gain adjust.

    VCA820 and VCA822 (which also have even faster variants).