ADRF6614

The ADRF6614 is a dual radio frequency (RF) mixer and intermediate frequency (IF) amplifier with an integrated phase-locked loop (PLL) and voltage controlled oscillators (VCOs). The ADRF6614 uses revolutionary broadband square wave limiting local oscillator (LO) amplifiers to achieve a wideband RF bandwidth of 700 MHz to 3000 MHz. Unlike narrow-band sine wave LO amplifier solutions, the LO can be applied above or below the RF input over a wide bandwidth. Energy storage elements are not utilized in the LO amplifier, thus dc current consumption also decreases with decreasing LO frequency.

The ADRF6614 utilizes highly linear, doubly balanced passive mixer cores with integrated RF and LO balancing circuits to allow single-ended operation. Integrated RF baluns allow optimal performance over the 700 MHz to 3000 MHz RF input frequency. The balanced passive mixer arrangement provides outstanding LO to RF and LO to IF leakages, excellent RF to IF isolation, and excellent intermodulation performance over the full RF bandwidth.

The balanced mixer cores provide extremely high input linearity, allowing the device to be used in demanding wideband applications where in-band blocking signals may otherwise result in the degra¬dation of dynamic range. Noise performance under blocking is comparable to narrow-band passive mixer designs. High linearity IF buffer amplifiers follow the passive mixer cores, yielding typical power conversion gains of 9.0 dB, and can be matched to a wide range of output impedances.

The PLL architecture supports both integer-N and fractional-N operation and can generate the entire LO frequency range of 200 MHz to 2700 MHz using an external reference input frequency anywhere in the range of 12 MHz to 320 MHz. An external loop filter provides flexibility in trading off phase noise vs. acquisition time. To reduce fractional spurs in fractional-N mode, a Σ-Δ modulator controls the post VCO-programmable divider. The device integrates six VCO cores, four of which provide complete frequency coverage between 200 MHz and 2700 MHz, and meet the GSM phase noise requirements in the 800 MHz and 900 MHz bands. Two additional GSM only cores enable the ADRF6614 to meet the GSM phase noise requirements in the digital cellular system 1800 MHz (DCS1800) and personal communications service 1900 MHz (PCS1900) bands.

All features of the ADRF6614 are controlled via a 3-wire SPI, resulting in optimum performance and minimum external components.

The ADRF6614 is fabricated using a BiCMOS, high performance IC process. The device is available in a 7 mm × 7 mm, 48-lead LFCSP package and operates over a −40°C to +85°C temperature range. An evaluation board is available.

Applications

• Multiband/multistandard cellular base station diversity receivers
• Wideband radio link diversity downconverters
• Multimode cellular extenders and picocells