Dual Digital VGA Reduces Solution Footprint by 32%

Maxim Integrated Products' MAX2063 fully programmable, multistate, dual-channel, digital IF/RF variable-gain amplifier (VGA) provides unique "rapid-fire" gain selection for four customized attenuation states per path, fast 25ns digital switching, and very low digital VGA amplitude overshoot/undershoot. It is an ideal choice for the "fast-attack" automatic gain control (AGC) circuits found in all 2.5G, 3G, 4G wireless infrastructure transceivers, including GSM/EDGE, CDMA, WCDMA, LTE, and WiMAX applications.

The MAX2063 can serve as either an IF or RF all-purpose VGA, interfacing directly with 50Ω systems operating over the 50MHz to 1GHz frequency range. Since the stages within each path have their own RF input and RF output, the MAX2063 can be configured to optimize either noise figure or linearity. In the latter configuration, the cascade yields a total gain range of 31dB, a maximum gain of 21.3dB, and a noise figure of only 5.6dB. The cascaded linearity is equally impressive with +41dBm of OIP3, +56dBm of OIP2, and +19dBm of OP1dB performance. In a receiver application, this excellent linearity directly enhances the receiver's immunity to strong blocker signals. Second- and third-order harmonic distortion (HD2 and HD3) is also limited to -54.8dBc and -72.9dBc, respectively. This performance eases the filtering requirements of close-in harmonics and leads to simpler and more cost-effective filter designs.

The device's unique rapid-fire gain-selection feature lets the user quickly access any of four customized digital attenuation states without incurring the delays associated with reprogramming the device through the SPI bus. The digital attenuator I/O is further reduced by a factor of either 5x or 2.5x (5 control bits vs. 1 or 2, respectively) depending on the number of states desired.

The MAX2063 incorporates five unique circuit functions into a single, compact monolithic device. When compared to an equivalent circuit using two MAX2066 VGAs, this new dual VGA reduces the circuit's overall footprint by 32 percent. These cost and space savings enable the next generation of wireless infrastructure designs in which transceiver price and density issues are paramount.

Maxim MAX2063 variable-gain amplifier

Maxim Integrated Products

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