Up-conversion Gain Research Articles

A 2-V, 1-10 GHz BiCMOS transceiver chip for multimode wireless communications networks

This paper concerns the design consideration, fabrication process, and performance results for an ultra-broadband, low-voltage, low-power, BiCMOS-based transceiver chip for cellular-satellite-LAN wireless communication networks. The transceiver chip incorporates an RF amplifier, a Gilbert down-mixer, and an IF amplifier in the receive path, and an IF amplifier, a Gilbert up-mixer, and an RF amplifier in the transmit path. For an RF frequency in the 1-10 GHz band and an IF frequency in the 100-1000 MHz band, the developed transceiver chip consumes less than 60 mW at 2 V, to yield a downconversion gain of 40 dB at 1 GHz and 10 dB at 10 GHz and an upconversion gain of 42 dB at 1 GHz and 11 dB at 10 GHz. To avoid possible start-up problems caused during "stand-by" to "enable" mode transition, a simple switching technique is employed for enabling either the receive or the transmit path, by changing the value of a reference voltage applied to both the down- and the up-mixers. While the developed transceiver chip exhibits the best performance for a dc supply voltage of 2 V, it shows a graceful degradation for a /spl plusmn/0.15 V voltage deviation. The transceiver's chip size is 1.04 mm/spl times/1.04 mm.

Intracavity upconversion lasing within a Q-switched Nd: YAG laser

Two-photon pumped upconversion intracavity lasing is achieved by placing a 1 cm-long dye-solution filled liquid cell inside a Q-switched Nd: YAG pulsed laser cavity. The upconversion gain medium is the solution of a new dye, trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium iodide, abbreviated as ASPI, which has strong two-photon absorption and subsequent upconversion fluorescence emission when excited with 1.06 μm laser radiation. The spectral, temporal, and spatial properties of the upconverted cavity lasing output are investigated. The key parameters for upconversion lasing are emission wavelength of ∼623 nm, pulse duration of ∼ (2–10) ns, and beam divergence of ∼(2.5–4) mrad. The corresponding parameters for the pump lasing from the same cavity are ∼ 1.06 μm, ∼ 20 ns, and ∼ (5–7) mrad, respectively. The net conversion efficiency from the absorbed IR pump laser pulse energy to the visible lasing pulse energy is measured to be ∼ 8.5%.

Quenching of NF singlet states in a hybrid chemical-laser system

Quenching of NF (a1Δ) and NF (b1Σ) was studied in a subscale upconversion gain medium that was based on energy transfer from NF (b1Σ) to IF. Quenching of NF (b1Σ) by IF was found to occur at gas-kinetic rates that were large compared to the energy-transfer rate, indicating low efficiency for the laser. Significant quenching of NF (a1Δ) by IF was also found to occur at a slower rate than was evident for the NF (b1Σ) state.

Parametric Energy Conversion by Nonlinear Admittances

The combination of nonlinear resistance (NR) and nonlinear capacitance (NC) elements for parametric frequency conversion shows promise for obtaining nonreciprocal features not present in pure NR or pure NC networks. This paper treats the simplest NR-NC combinations consisting of a single NR element connected either in series or in parallel with a single NC element. When the NR and NC elements are "pumped" in time quadrature, such circuits are capable of yielding unconditionally stable up-conversion gains, for both the inverting and noninverting case, considerably in excess of the output-to-input frequency ratios. Simultaneously, the down-conversion loss can be made infinite at one frequency and considerably in excess of the up-conversion gain over a band of frequencies. With ideal NR and NC elements, the maximum available up-conversion gain to either an inverted or noninverted sideband with unconditional stability (|down-conversion loss|≥|up-conversion gain|) approaches the square of the output-to-input frequency ratio.