高频电子线路习题答案（第五版）张肃文(5)

22VcmVCC2426?10解：R1?Rp????144???2P02P02?2XC1?C1?R1144??14.4???QL1011?pF???22162?fXC12?3.14?50?10?14.4R2R22?QL?1??1R1?200200??100?1??1144?16.95???XL1?L1?XL116.95??0.054??H?62?f2?3.14?50?102?1?RP增加一倍，放大器工作6?11解：于过压状态，Vcm变化不大，P0??Vcm/2RP?0.5P0；2?2?RP减小一半，放大器工作于欠压状态，Icm变化不大，P0??IcmRP/2?2P0。?10?144?QLR1?R2200????1??1???2.57???2??QL?1?QLXL1?100?1?10?16.95?11?pF?C2???12392?fXC22?3.14?50?106?2.57 XC2?6?12解：?k?r???r1?r1?

22?VCC?VCE?sat??Vcm?12?0.5?6?13解：RP????66???2P02P02?12111???57.4%?L1?L2111?1?22QQk100?15?0.032Q1Q2??M?12

设QL?10C1?则XC1?RP66??6.6???QL1011??241?pF?2?fXC12?3.14?108?6.6RLR?1?Q?R2LLXC2???150P?1?10??50?1662?5.5???C2?11??290?pF?2?fXC22?3.14?108?5.5QLRP?RL?10?66?50???1??1?2?102?1?10?5.5??12.5???QL?1?QX??LC2??

XL1?L1?XL112.5??19.9?nH?82?f2?3.14?10?C1?和R???a?将R1C1和R2C2串联电路改为R16?14证：XC1?2C2并联电路，并设2XCR1??212R1R1?XC12XC??222R2R2R2?XC2R1QL2R2?2?2XCXC22R2?XC2R12?1?2XCXC12R1?XC122XCXC11?，即R1??2匹配时R1??R2R1?R1?222R222R1?XC11?QLR2?XC2?XC2?R2?1?Q?RR2L2?11XL12R12R2?1?XC?2?2?XCXC1?2XC222R1?XC1R2?XC22XCR12R1R2R1QL1R1R2R1QL1?2X??????C122222R1?XCR12?XCXC21?QL1?QLXC21?QL11?R2??1??QX??LC2???C1?和R???b?将R1C1和R2L1串联电路改为R1XC1?2L1并联电路，并设2XCR1??212R1R1?XC12XL1??2R2R22R2?XL1R1QL2R2??2XL1XL12R2?XL1R12?1?2XCXC12R1?XC122XC1XL11?，即R1??2匹配时R1??R2R1?R1?2R2222R1?XC11?QLR2?XL1?XL1?R2?1?Q?RR2L2?11XC22R2R12?1?XC?1?2?XLXL1?2XC122R2?XL1R1?XC12XCRRRQRQR2RQRQ?212?12?1L2?1L2??1L2?1L2R1?XC1XL11?QL1?QLQLXL11?QL1?QL?R2????1?QX??LL1??1?天线断开，工作于过压6?18解：状态，集电极直流电表读数减小，天线电流表读数为0；?2?天线接地，工作于欠压状态，集电极直流电表读数略增，天线电流表读数增加；?3?中介回路失谐，工作于欠压状态，集电极直流电表读数略增，天线电流表读数减小。?1?PA?P??PC?Pk?10?3?1?6?W?6?19解：?2??k?PA6??85.7%P??PC10?3P??10?3?70?3??c?P??PC??PA6??60%P?10

6?20解：当k?kc时，?k?1???1?若?k6?25解：

r1?50%则r??r1r1?r?1?Q1Q2kc?1Q01QQ09?3?3kcQ

r1?90%则r???9r1故k?r1?r??

6?27解：??2?60o???1?60o?，?P0减小，工作于欠压状态。

VV6?28解：Ri??93?9RLI3I

V?VBB0.6?1.456?29解：Vbm?BZ??6?V?ocos?cos70VB?Vbm?VBB?6?1.45?4.55?V?iCmax?Icm1P0?VB?VBZ4.55?0.6??1.98?A?22?iCmax?1?70o??1.98?0.436?0.86?A?Vcm?VCC?gcriCmax?24?1.98?22.02?V?Icm1Vcm0.86?22.01??9.47?W?22?QL?10???PA??1?P?1????9.47?8.52?W?0??Q0??100??

6?30解：Vbm?VBZ?VBB0.6?1.5??6.14?V?cos?cos70oVB?Vbm?VBB?6.14?1.5?4.64?V?iCmax?Icm1P0?VB?VBZ4.64?0.6??2.02?A?22?iCmax?1?70o??2.02?0.436?0.88?A?Vcm??VCC?0.9?24?21.6?V?Icm1Vcm0.88?21.6??9.5?W?22?QL?10???PA??1?P?1????9.5?8.8?W??Q?0100??0??

?a?电路可能振荡，属于电7?5解：感反馈式振荡电路；?e?电路可能振荡，属于电容反馈式振荡电路；?h?电路可能振荡，属于电容反馈式振荡电路；?b?、?c?、?d?电路不可能振荡；?f?电路在L2C2?L3C3时有可能振荡，属于电容反馈式振荡电路?g?电路计及Cbe可能振荡，属于电容反馈式振荡电路。 ?1?有可能振荡，属于电容7?6解：反馈式振荡电路，f1?f2?f0?f3；?2?有可能振荡，属于电感反馈式振荡电路，f1?f2?f0?f3；?4?有可能振荡；属于电容反馈式振荡电路，f1?f2?f0?f3；?3??5??6?不可能。

7?7解：

?1?f0?7?21解：11??100?MHz??7?122πL?C?Cd?2?3.14?10??20?5??10C1??L36?2?gd?1?1RPQ?3?0.06~0.08V?1?fq?7?26解：6?20?5??10?1210?7?5.27?mS?

?1?1.5~1.5001?MHz?7?27解：1.657?101.657?10??4.14?MHz?d0.4S200Cq?21.1?10?5?21.1?10?5??0.105?pF?d0.4d30.43Lq?43.5?43.5??14?mH?S200d0.4rd?42500B?42500?0.25??21.2?Ω?S200S200C0?3.96?10?2?3.96?10?2??19.8?pF?d0.41.051.05Qq??104d??104?0.4?16800B0.251.657?1061.657?106?2?d???0.11?mm?6fq15?10

?2?不能?3?不能，普通三极管没有负阻特性。

7?28解：恒温槽、稳压电源、高稳定度克拉泼振荡电路、共集电极缓冲级等。

7?29解：并联c?b型（皮尔斯）晶体振荡电路。

9?3解：i?I?1?macosΩt?cosω0t?Icosω0t?I有效值IImacos?ω0?Ω?t?macos?ω0?Ω?t22222?I??I??I???ma???ma?????2??22??22?2maI?1?22

?1?v?25?1?0.7cos2π5000t?0.3cos2π100009?4解：t?sin2π106t??25sin2π106t?8.75?sin2π1005000?sin2π995000??3.75?sin2π1010000?sin2π990000?2?包络25?1?0.7cos2π5000t?0.3cos2π10000t?V?V025??1?0.7?0.3??25峰值调幅度m?max??0.4上V025V0?Vmin25?25?1?0.7?0.3???1V025

121?1?ma?1时9?5解：P?ω0?Ω??P?ω0?Ω??maP0T??100?25?W?44121?2?ma?0.3时P?ω0?Ω??P?ω0?Ω??maP0T??0.32?100?2.25?W?44

39?6解：i?b1v?b3v不包含平方项，不能产生调幅作用。

?1?P?ω0?Ω??P?ω0?Ω??1ma2P0T?1?0.72?5000?612.5?W?9?7解：44?W?P?ω0?Ω??2P?ω0?Ω??1225谷值调幅度m下??2?P??P0avη?P0T5000??10?kW?η0.52???ma0.72??P0T?1???5000???1?2??2P0av?????12.45?kW??3?P????ηη0.5

?1?ma?1时9?8解：121maP0T??1000?250?W?44?W?P0?P0T?P?ω0?Ω??P?ω0?Ω??1000?250?250?1500P?ω0?Ω??P?ω0?Ω???2?ma?0.7时121maP0T??0.72?1000?122.5?W?44?W?P0?P0T?P?ω0?Ω??P?ω0?Ω??1000?122.5?122.5?1245P?ω0?Ω??P?ω0?Ω???kHz? 9?9解：f?f0?f1?f2?f3?f4?5?20?200?1780?8000?10005