These extremely broadband Darlington amplifiers can be used unmatched for a wide range of applications, or output matched for continuous-frequency requirements.
Gain blocks are invaluable "amplitude adjustment" devices for a wide range of circuits and systems. Since such gain blocks are often used in broadband applications, Celeritek (Santa Clara, CA) has added two extremely broadband devices to its line of monolithic-microwave-integrated-circuit (MMIC) gain blocks, models CGB7014-SC and CGD7017-SC. Based on proprietary InGaP process technology, the heterojunction-bipolar-transistor (HBT) based gain blocks can be used for applications from 0.1 to 6.0 GHz, providing as much as 23 dB gain at 2 GHz. Both cascadable Darlington devices are in die form or in compact SOT-89 packages with excellent electrostatic-discharge (ESD) protection and low thermal resistance.
The gain blocks employ a trusted Darlington configuration. Darlington-pair gain blocks have been in use for more than 50 years. Most feature low gain with relatively flat response over frequency or high gain with more widely varying gain response versus frequency. Both amplifiers can be used for a wide range of applications, including cellular systems, wireless local-area networks (WLANs), and satellite communications systems. In addition, with simple output matching, the CGB7017-SC can provide relatively flat gain response (Fig. 1) for applications requiring broadband, continuous coverage within the 0.1-to-6.0-GHz band.
Model CGB7014-SC is rated for 24.5-dB typical small-signal gain at 850 MHz and 18.5-dB gain at 6 GHz. It achieves +20.3-dBm typical output power at 1-dB compression at 850 MHz with +10-dBm typical output power at 6 GHz. The output third-order intercepts at those two frequencies are +36 and +19 dBm, respectively, while the noise figures are typically 3.5 and 4.5 dB, respectively. It should be noted that these performance levels apply for all temperatures within the range of –40 to +85°C.
Model CGB-7017-SC provides 23.1-dB typical small signal gain at 850 MHz and 19.5-dB typical small-signal gain at 6 GHz. It has typical output power at 1-dB compression of +18.2 dBm at 850 MHz and +12 dBm at 6 GHz. The output third-order intercepts at those two frequencies are +33.8 and +20.3 dBm, respectively, while the noise figures are typically 3.3 and 4.6 dB, respectively. As with the CGB-7014-SC, these performance levels apply for all temperatures within the range of –40 to +85°C. In fact, both devices are unconditionally stable over that temperature range under small-signal conditions. Above 2 GHz, the CGB7014 is unconditionally stable for all output powers. The CGB7017 is unconditionally stable at all output powers at frequencies above 3.5 GHz. For both gain blocks, the gain flatness is typically about ±0.75 dB over that temperature range and frequencies from 0.1 to 3.5 GHz and ±1.5 dB over the full temperature range and frequencies from 0.1 to 6.0 GHz.
Both gain-block models are rated for maximum RF input power of +17 dBm and ESD of 1000 V. The maximum device current is 130 mA, maximum voltage is 6 V, and the maximum dissipated power is 650 mW. Neither gain block requires impedance matching but, with the addition of simple output matching circuitry (Fig. 2), the gain-versus-frequency response of the CGB7017-SC can be flattened from 0.1 to 6.0 GHz. P&A: stock. Celeritek, Inc., 3236 Scott Blvd., Santa Clara, CA 95054; (408) 986-5060, FAX: (408) 986-5095, Internet: www.celeritek.com.