EFJohnson 7780 Circuit Description, Power Switching and Regulation, Synthesizer Description

CIRCUIT DESCRIPTION

SECTION 4 CIRCUIT DESCRIPTION

127(￿￿$￿EORFN￿GLDJUDP￿RI￿WKH￿5)￿DQG￿ORJLF￿XQLWV￿LV￿ ORFDWHG￿RQ￿SDJH￿￿￿￿￿

4.1 POWER SWITCHING AND REGULATION

4.1.1 POWER SWITCHING

8QVZLWFKHG￿EDWWHU\￿YROWDJH￿LV￿DSSOLHG￿WR￿WKH￿

SRZHU￿DPSOLILHU￿PRGXOH￿DQG￿SRZHU￿FRQWURO￿FLUFXLW￿LQ￿ WKH￿5)￿XQLW￿￿2WKHUZLVH￿￿DOO￿SRZHU￿LV￿VZLWFKHG￿E\￿

3￿FKDQQHO￿026)(7V￿4￿￿￿￿DQG￿4￿￿￿￿LQ￿WKH￿ORJLF￿ XQLW￿￿7KH￿/9&&￿VXSSO\￿LV￿SURGXFHG￿E\￿4￿￿￿￿DQG￿WKH￿ 9&&￿VXSSO\￿LV￿SURGXFHG￿E\￿4￿￿￿￿￿:KHQ￿WKH￿RQ￿RII￿

VZLWFK￿LV￿WXUQHG￿RQ￿￿WKH￿RXWSXW￿RI￿VZLWFKLQJ￿WUDQVLVWRU￿ 4￿￿￿￿JRHV￿ORZ￿ZKLFK￿WXUQV￿4￿￿￿￿DQG￿4￿￿￿￿RQ￿￿7KLV￿ DSSOLHV￿VZLWFKHG￿￿￿￿￿YROWV￿WR￿￿￿YROW￿UHJXODWRUV￿,&￿￿￿￿

DQG￿,&￿￿￿￿￿WKH￿DXGLR￿DPSOLILHU￿VWDJHV￿￿DQG￿RWKHU￿SDUWV￿ RI￿WKH￿WUDQVFHLYHU￿￿

:KHQ￿WKH￿SRZHU￿VZLWFK￿LV￿WXUQHG￿RII￿￿WKH￿EDVH￿RI￿ 4￿￿￿￿LV￿SXOOHG￿ORZ￿E\￿5￿￿￿￿ZKLFK￿WXUQV￿4￿￿￿￿RII￿DQG￿ WKH￿FROOHFWRU￿JRHV￿KLJK￿￿+RZHYHU￿￿EHFDXVH￿RI￿GLRGH￿ '￿￿￿￿￿4￿￿￿￿DQG￿4￿￿￿￿GR￿QRW￿WXUQ￿RII￿XQWLO￿&￿￿￿￿

FKDUJHV￿WKURXJK￿5￿￿￿￿￿7KLV￿SURYLGHV￿D￿VOLJKW￿WXUQ￿RII￿ GHOD\￿WR￿JLYH￿WKH￿PLFURSURFHVVRU￿WLPH￿WR￿WDNH￿RYHU￿

SRZHU￿RII￿FRQWURO￿￿7KH￿PLFURSURFHVVRU￿LPPHGLDWHO\￿ GHWHFWV￿SRZHU￿WXUQ￿RII￿E\￿PRQLWRULQJ￿WKH￿2))5(4,￿ VLJQDO￿RQ￿SLQ￿￿￿￿￿,W￿WKHQ￿FKDQJHV￿WKH￿2))5(4￿RXWSXW￿ RQ￿SLQ￿￿￿￿WR￿D￿KLJK￿OHYHO￿ZKLFK￿WXUQV￿4￿￿￿￿DJDLQ￿RQ￿

XQWLO￿FXUUHQW￿VHWWLQJV￿KDYH￿EHHQ￿VDYHG￿WR￿PHPRU\￿DQG￿ RWKHU￿UHTXLUHG￿SRZHU￿GRZQ￿IXQFWLRQV￿KDYH￿EHHQ￿ SHUIRUPHG￿￿

4.1.2 5-VOLT REGULATORS (IC401, IC402)

5HJXODWRU￿,&￿￿￿￿LQ￿WKH￿ORJLF￿XQLW￿SURYLGHV￿WKH￿ ￿￿/￿￿￿9￿￿ORJLF￿VXSSO\￿￿DQG￿UHJXODWRU￿,&￿￿￿￿SURYLGHV￿ WKH￿￿￿9￿VXSSO\￿￿7KH￿￿￿9￿VXSSO\￿LV￿LQ￿WXUQ￿VZLWFKHG￿ E\￿4￿￿￿￿4￿￿￿￿WR￿SURYLGH￿WKH￿5￿9￿￿7￿9￿￿DQG￿￿￿6￿

VXSSOLHV￿￿7KHVH￿WUDQVLVWRUV￿DUH￿FRQWUROOHG￿E\￿VLJQDOV￿ IURP￿WKH￿PLFURSURFHVVRU￿￿

7KH￿ORZ￿EDWWHU\￿GHWHFW￿VLJQDO￿LV￿SURYLGHG￿E\￿D￿ YROWDJH￿GLYLGHU￿IRUPHG￿E\￿5￿￿￿￿DQG￿5￿￿￿￿￿7KHVH￿ UHVLVWRUV￿GLYLGH￿GRZQ￿WKH￿￿￿￿9￿9FF￿VXSSO\￿WR￿SURGXFH￿ WKH￿%$7,1￿VLJQDO￿WKDW￿LV￿DSSOLHG￿WR￿SLQ￿￿￿￿RI￿WKH￿

PLFURSURFHVVRU￿

4.2 SYNTHESIZER DESCRIPTION

4.2.1 INTRODUCTION

7KH￿V\QWKHVL]HU￿RXWSXW￿VLJQDO￿LV￿SURGXFHG￿E\￿D￿ 9&2￿￿9ROWDJH￿&RQWUROOHG￿2VFLOODWRU￿￿LQ￿WKH￿5)￿XQLW￿￿ 7KH￿9&2￿IUHTXHQF\￿LV￿FRQWUROOHG￿E\￿D￿'&￿YROWDJH￿ SURGXFHG￿E\￿WKH￿SKDVH￿GHWHFWRU￿LQ￿V\QWKHVL]HU￿FKLS￿ ,&￿￿￿7KH￿SKDVH￿GHWHFWRU￿VHQVHV￿WKH￿SKDVH￿DQG￿ IUHTXHQF\￿RI￿WKH￿WZR￿LQSXW￿VLJQDOV￿￿2QH￿VLJQDO￿LV￿WKH￿ UHIHUHQFH￿IUHTXHQF\￿IURP￿7&;2￿;￿￿DQG￿WKH￿RWKHU￿LV￿ IURP￿WKH￿9&2￿￿,I￿WKHVH￿VLJQDOV￿DUH￿QRW￿WKH￿VDPH￿ IUHTXHQF\￿￿WKH￿SKDVH￿GHWHFWRU￿FKDQJHV￿WKH￿9&2￿ FRQWURO￿YROWDJH￿ZKLFK￿FKDQJHV￿WKH￿9&2￿IUHTXHQF\￿ XQWLO￿ERWK￿VLJQDOV￿DUH￿V\QFKURQL]HG￿￿7KH￿9&2￿LV￿WKHQ￿ ³ORFNHG´￿RQ￿IUHTXHQF\￿￿

&KDQQHOV￿DUH￿VHOHFWHG￿E\￿SURJUDPPLQJ￿WKH￿ FRXQWHUV￿LQ￿,&￿￿WR￿GLYLGH￿E\￿GLIIHUHQW￿QXPEHUV￿￿7KLV￿

SURJUDPPLQJ￿GDWD￿FRPHV￿IURP￿WKH￿PLFURSURFHVVRU￿RQ￿ WKH￿ORJLF￿ERDUG￿￿7KH￿IUHTXHQF\￿VWDELOLW\￿RI￿WKH￿V\QWKH￿ VL]HU￿LQ￿ERWK￿WKH￿UHFHLYH￿DQG￿WUDQVPLW￿PRGHV￿LV￿GHWHU￿ PLQHG￿E\￿WKH￿VWDELOLW\￿RI￿7&;2￿;￿￿￿7KH￿VWDELOLW\￿RI￿ WKLV￿GHYLFH￿LV￿￿￿￿￿330￿IURP￿±￿￿ƒ￿WR￿￿￿￿￿ƒ￿)￿￿±￿￿ƒ￿WR￿

￿￿￿ƒ￿&￿￿￿7KH￿9&2￿RXWSXW￿VLJQDO￿LV￿EXIIHUHG￿DQG￿WKHQ￿ IHG￿WR￿WKH￿UHFHLYHU￿DV￿WKH￿ILUVW￿LQMHFWLRQ￿VLJQDO￿DQG￿WR￿

WKH￿WUDQVPLWWHU￿DV￿WKH￿WUDQVPLW￿VLJQDO￿

4.2.2 VCO (IC3), BUFFERS (Q10-Q12)

6XSSO\￿YROWDJH￿WR￿9&2￿,&￿￿LV￿IURP￿&39￿UHJX￿ ODWRU￿,&￿￿DQG￿DFWLYH￿ILOWHU￿4￿￿RQ￿WKH￿,)￿ERDUG￿￿4￿￿

IXQFWLRQV￿DV￿D￿FDSDFLWDQFH￿PXOWLSOLHU￿WR￿SURYLGH￿ ILOWHULQJ￿RI￿WKH￿￿￿YROW￿VXSSO\￿WR￿WKH￿9&2￿￿5￿￿DQG￿]HQHU￿ GLRGH￿'￿￿SURYLGH￿ELDV￿￿DQG￿&￿￿SURYLGHV￿WKH￿FDSDFL￿ WDQFH￿WKDW￿LV￿PXOWLSOLHG￿￿,I￿D￿QRLVH￿SXOVH￿RU￿RWKHU￿

YROWDJH￿FKDQJH￿DSSHDUV￿RQ￿WKH￿FROOHFWRU￿￿WKH￿EDVH￿ YROWDJH￿GRHV￿QRW￿FKDQJH￿EHFDXVH￿RI￿&￿￿DQG￿'￿￿￿7KHUH￿ IRUH￿￿LW￿GRHV￿QRW￿DSSHDU￿RQ￿WKH￿HPLWWHU￿￿

7KH￿9&2￿FRQWURO￿YROWDJH￿LV￿DSSOLHG￿WR￿SLQ￿￿￿RI￿ ,&￿￿￿DQG￿WKH￿WUDQVPLW￿DXGLR￿GDWD￿PRGXODWLRQ￿VLJQDO￿LV￿ DSSOLHG￿WR￿SLQ￿￿￿￿7KH￿PRGXODWLRQ￿VLJQDO￿LV￿DOVR￿DSSOLHG￿ WR￿WKH￿7&;2￿DV￿GHVFULEHG￿LQ￿WKH￿QH[W￿VHFWLRQ￿￿7KH￿ RXWSXW￿VLJQDO￿RI￿WKH￿9&2￿RQ￿SLQ￿￿￿LV￿DSSOLHG￿WR￿D￿

7￿VSOLWWHU￿IRUPHG￿E\￿5￿￿￿5￿￿￿￿7KLV￿QHWZRUN￿URXWHV￿WKH￿ 9&2￿VLJQDO￿WR￿EXIIHU￿DPSOLILHUV￿4￿￿￿4￿￿￿DQG￿DOVR￿WR￿ 4￿￿￿￿7KHVH￿VWDJHV￿SURYLGH￿DPSOLILFDWLRQ￿DQG￿LVRODWH￿

	November 1999
4-1	Part No. 001-7780-500