Until the advent of cellular communications and other wireless technologies, the microwave industry was mostly defense-focused. Once wireless communications came on the scene, however, everything shifted. Given the large volumes projected by cellular marketing professionals, many companies reorganized to make serving this market their priority. Of course, when wireless markets dropped in the late 1990s, those same companies had to remind customers about their "defense roots." Some were then acquired, absorbed, or simply ran out of money. Yet the large number of firms involved until that point helped push cellular communications technology on the path of continuous improvement that it still travels today.
In the April 1998 issue, for example, a dual-chip solution was heralded for its support of Global System for Mobile Communications (GSM) handsets. Hailing from CommQuest Technologies, Inc. (Encinitas, CA), this tri-band solution targeted digital cellular and Personal Communications Services (PCS) GSM-based handsets. The dual-integrated-circuit (IC) solution comprised a transceiver and the firm's own Communication Application Specific Processor (CASP). The transceiver incorporated several mixers and two on-chip voltage-controlled oscillators (VCOs) that worked with ultra-high-frequency (UHF) and very-high-frequency (VHF) phase-locked-loop (PLL) synthesizer circuits on the processor IC.
In a typical architecture (Fig. 1), the transceiver required what was then considered to be very few additional components, such as a transmit VCO, transmit power amplifiers (PAs), receiver low-noise amplifiers (LNAs), and transmit/receive (T/R) switches. A 1-b sampling technique was used to eliminate the last intermediate-frequency (IF) downconversion and in-phase/quadrature (I/Q) demodulation stages. Although such architectures look complex by today's standards, innovations like this one began cellular handsets' drive toward integration. As for CommQuest, it was acquired in 1998 by International Business Machines Corp. (IBM).
Of course, cellular developments have relied heavily on test and measurement innovations. The spring of 1998 also saw the introduction of a handheld analyzer that verified RF field strength. Although such handheld instruments are a common tool for today's field technicians, they were considered novel 10 to 15 years ago. Obviously, they also boasted simpler functionality and capabilities. The model 3201 field-strength analyzer from Protek (Northvale, NJ), for example, made measurements from 100 kHz to 2060 MHz (Fig. 2). It came in a size that was then considered compact: 9 x 4 x 1.77 in. at 1.4 lbs. The field-strength analyzer could be automatically swept across a frequency range, tuned according to stored frequencies, or tuned manually in selected frequency steps. Again, it is a far cry from today's cutting-edge productsbut it should be appreciated as their forerunner.
