| 摘要 |
<p>1,128,068. Synchronous demodulators for colour television. BLAUPUNKT-WERKE G.m.b.H. 14 Jan., 1966 [15 Jan., 1965], No. 1770/66. Headings H3T and H4F. A transistor 30 functions as a common emitter stage to supply the reference carrier to a pushpull synchronous demodulator 36, 37, and as a common collector stage to supply the demodulation product (i.e. R-Y, B-Y, I or Q) to the output. Filter 32, 52, 53 (or a resonant rejector circuit) presents a low impedance at carrier frequency, transformer 33 presents a low impedance at the frequency of the demodulation products and inductor 44 presents a high impedance at carrier frequency. In a modification, Fig. 2 (not shown), transistor (20) functions as a common base stage to apply the reference carrier to demodulator (22) and as a common collector stage to supply the demodulation products on lead (24) to the output. Circuits (21) and (25) are resonant at carrier frequency.</p> |
