Date: 06/02/2009

Low distortion differential RF/IF amplifiers to drive high-frequency ADCs

Analog Devices launched two differential amplifiers, ADL5561 and ADL5562, which can efficiently drive high-speed, high-IF sampling ADCs required by, advanced communications systems. These devices are capable of maintaining performance while driving ADCs even up to 500 MHz.

Key features and advantages are:

1. On-chip, user-selectable gain-setting resistors enable detailed specifications at common IF frequencies (70 MHz, 100 MHz, 140 MHz, and 250 MHz) and common gain settings (6 dB, 12 dB, 15.5 dB).
2. The pin-compatible ADL5561 and ADL5562 allow the user to select power consumption and performance to meet the requirements for a given application.
3. The ADL5561 and ADL5562 amplifiers can drive 12- to 16-bit ADCs at the practical IF frequencies for use in communications systems, such as 3G LTE (Long-Term Evolution) and NGMN (Next Generation Mobile Networks).
4. Lowering the distortion level of the ADC driver improves system performance at higher frequencies by maximizing the receive channel's SFDR (spurious free dynamic range) and minimize its SNR (signal-to-noise-ratio).
5. Minimizes the number of IF frequencies within the radio design, resulting in lower power, cost, component count, and board area, and advancing system-level performance in applications such as wireless base stations, cable communications, medical and instrumentation, military and satellite communications.
6. The 2-GHz ADL5561 differential amplifier consumes just 40 mA, making it suited for use in sub-140 MHz IF applications.
7. The ADL5561 achieves distortion levels of -86 dBc HD2, -88 dBc HD3, and -95 dBc IMD3 at 100 MHz.
8. The 2.6 GHz ADL5562 differential amplifier consumes 80 mA, making it suitable for IF applications up to 500 MHz.
9. The ADL5562 achieves distortion levels of -95 dBc HD2, -86 dBc HD3, and -96 dBc IMD3 at 140 MHz.
10. Both the ADL5561 and ADL5562 operate on a 3-volt power supply
11. Unlike conventional GaAs differential amplifiers, which often require the use of a transformer to perform the single-ended to differential conversion, the ADL5561 and ADL5562 can operate in fully differential circuits or provide the single-ended to differential conversion.

Package: 3 mm × 3 mm LFCSP
Price: Both devices cost $3.68 per unit in 1,000-piece quantities
Availability: Sampling now production volumes in April 2009.

For more information, visit: www.analog.com/RF