TI adds gain control to differential amplifier
The LMH6882 is a high-speed, high-performance programmable differential amplifier. With a bandwidth of 2.4 GHz and high linearity of 42 dBm OIP3, the LMH6882 is suitable for a wide variety of signal conditioning applications.
The LMH6882 programmable differential amplifier combines the best of both fully Differential amplifiers and variable gain amplifiers. It offers superior noise and distortion performance over the entire gain range without external resistors, enabling the use of just one device and one design for multiple applications requiring different gain settings.
The LMH6882 is an easy-to-use amplifier that can replace both fully differential, fixed gain amplifiers as well as variable gain amplifiers. The LMH6882 requires no external gain-setting components and supports gain settings from 6 dB to 26 dB with small, accurate 0.25-dB gain steps. As shown in the chart below the gain steps are very accurate over the entire gain range. With an input impedance of 100 Ω the LMH6882 is easy to drive from a variety of sources such as mixers or filters. The LMH6882 also supports 50 Ω single ended signal sources and supports both DC- and AC-coupled applications.
Parallel gain control allows the LMH6882 to be soldered down in a fixed gain so that no control circuit is required. If dynamic gain control is desired, the LMH6882 can be changed with SPI serial commands or with the parallel pins.
The LMH6882 is fabricated in TI’s CBiCMOS8 proprietary complementary silicon germanium process and is available in a space saving, thermally enhanced 36-pin WQFN package. The same amplifier is offered in a single package as the LMH6881.
- Small Signal Bandwidth: 2400 MHz
- OIP3 @ 100 MHz: 42 dBm
- HD3 @ 100 MHz: −100 dBc
- Noise Figure: 9.7 dB
- Voltage Gain: 26 dB to 6 dB
- Voltage Gain Step Size 0.25 dB
- Input Impedance 100Ω
- Parallel and Serial Gain Control
- Power Down Capability
Texas Instruments has introduced its first differential amplifiers which are programmable for variable gain.
The 2.4GHz LMH6881 single-channel and 2.4GHz LMH6882 dual-channel amplifiers have a 6dB to 26dB gain range.
“The programmable gain control in the LMH6881 and LMH6882 eliminates the need for gain-setting resistors and their associated mismatch errors, enabling more robust systems for applications, such as medical, test and measurement, military, wireless communications, and microwave backhaul,” said the supplier.
Noise figures at maximum gain (26dB) and 100MHz input frequency are: 9.7dB noise figure, 44-dBm OIP3, and -100 dBc HD3.
Gain control can be implemented via SPI bus or dedicated pins, with no external resistors needed.
The devices support DC/AC coupling and single-ended-to-differential conversion which can remove the need for a balun.
The LMH6882’s channel gain matching is 0.2dB and phase matching is 1.5 degrees, which provides image rejection for wideband zero IF and I/Q sampling applications.
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