Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – Integrated structure
Reexamination Certificate
2002-03-05
2002-12-31
Callahan, Timothy P. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
Integrated structure
C257S499000
Reexamination Certificate
active
06501330
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a technology of reducing cross talk in a semiconductor integrated circuit and a technology effectively applicable to a signal-processing LSI (or a large-scale semiconductor integrated circuit) for receiving and processing signals in a plurality of different frequency bands. More particularly, the present invention relates to a technology effectively applicable to a radio-communication LSI employed typically in a hand phone for processing a signal received by adoption of a super-heterodyne technique.
As a radio-communication system adopted in a hand phone, there is known a radio-communication system embracing the super-heterodyne technique as shown in FIG.
11
. In the radio-communication system shown in
FIG. 11
, reference numeral
100
denotes an antenna for receiving a signal wave and reference numeral
101
denotes a reception/transmission changeover switch. Reference numeral
110
denotes a reception-system circuit for amplifying the signal received by the antenna
100
and demodulating the amplified signal. Reference numeral
120
denotes a transmission-system circuit for modulating a signal to be transmitted through the antenna
100
and converting the frequency of the signal. Reference numeral
130
is an oscillation-system circuit for generating a local oscillation signal required by the reception-system circuit
110
and the transmission-system circuit
120
. Reference numeral
140
denotes a base-band-signal-processing circuit for carried out processing such as extraction of audio data from a signal received by the antenna
100
and conversion of the audio data into a train of voltage pulses. Reference numeral
150
is a system controller including a microcomputer for totally controlling the entire radio-communication system. The transmission/reception changeover switch
101
is controlled by a control signal TX/RX output by the system controller
150
to switch the mode of the radio-communication system from reception to transmission and vice versa.
The reception-system circuit
110
comprises a band-limiting filter (FLT)
111
, a low-noise amplification circuit (LNA)
112
, a down-conversion mixer (MIX)
113
, a band-pass filter (BPF)
114
, a programmable-gain amplifier (PGA)
115
and a demodulator (DeMOD)
116
. The FLT
111
is typically an SAW filter for removing unnecessary waves from a signal received by the antenna
100
. The LNA
112
is an amplifier for amplifying a signal passing through the band-limiting filter (FLT)
111
. The MIX
113
is a converter for down-converting the frequency of the signal amplified by the amplification circuit (LNA)
112
into an intermediate frequency by mixing the signal with the local oscillation signal generated by the oscillation-system circuit
130
. The BPF
114
is a filter for passing through a signal having the frequency corresponding to a difference in frequency between the signal amplified by the amplification circuit (LNA)
112
and the local oscillation signal. The programmable-gain amplifier (PGA)
115
is an amplifier capable of controlling a gain at which a signal output by the band-pass filter (BPF)
114
is amplified thereby to a desired level. The DeMOD
116
is a demodulator for modulating the signal with the amplitude thereof adjusted by the programmable-gain amplifier (PGA)
115
to a desired level into a base-band signal (I/Q).
The transmission-system circuit
120
comprises a modulator (MOD)
121
, an up-conversion mixer (U-MIX)
122
and a power amplifier (PA)
123
. The MOD
121
is a modulator for modulating a signal to be transmitted into an RF (radio frequency) signal. The signal to be transmitted is received from the base-band-signal-processing circuit
140
as a base-band signal (I/Q). The mixer (U-MIX)
122
is a converter for up-converting the frequency of the signal obtained as a result of modulation by the modulator (MOD)
121
into a desired transmission frequency by mixing the modulated signal with the local oscillation signal generated by the oscillation-system circuit
130
. The PA
123
is an amplifier for amplifying the power of the signal to be transmitted after the frequency conversion prior to a transmission by way of the antenna
100
.
The oscillation-system circuit
130
comprises a radio-frequency voltage-controlled oscillation circuit (RFVCO)
132
, an intermediate-frequency voltage-controlled oscillation circuit (IFVCO)
131
, a synthesizer (SYN)
133
and a buffer (BFF)
134
. The RFVCO
132
is a voltage-controlled oscillation circuit for generating an RF (radio frequency) signal used in the down-conversion mixer (MIX)
113
and the up-conversion mixer (U-MIX)
122
. On the other hand, the intermediate-frequency voltage-controlled oscillation circuit (IFVCO)
131
is a voltage-controlled oscillation circuit for generating an IF (intermediate frequency) signal, that is, a signal with a fixed frequency, required by the demodulator (DeMOD)
116
and the modulator (MOD)
121
. The SYN
133
is a synthesizer for generating control voltages applied to the radio-frequency voltage-controlled oscillation circuit (RFVCO)
132
and the intermediate-frequency voltage-controlled oscillation circuit (IFVCO)
131
respectively. The control voltage applied to each of the VCO
131
and VCO
132
is generated in accordance with a difference in phase between a feedback signal generated by the VCO
131
and VCO
13
and a reference signal TCXO generated by an oscillation circuit employing a crystal oscillator exhibiting characteristics of high frequency precision and little temperature dependence. The difference in phase is obtained as a result of comparing the feedback signal with the reference signal TCXO. The BFF
134
is a buffer for supplying an oscillation signal generated by the RFVCO
132
to the down-conversion mixer (MIX)
113
employed in the reception-system circuit
110
and the up-conversion mixer (U-MIX)
122
employed in the transmission-system circuit
120
by proper distribution. It should be noted that the synthesizer (SYN)
133
and the radio-frequency voltage-controlled oscillation circuit (RFVCO)
132
constitute a closed-loop circuit known as a PLL (Phase Locked Loop) circuit. Similarly, the synthesizer (SYN)
133
and the intermediate-frequency voltage-controlled oscillation circuit (IFVCO)
131
constitute another closed-loop circuit also known as a PLL (Phase Locked Loop) circuit.
SUMMARY OF THE INVENTION
The radio-communication system shown in
FIG. 11
comprises about 10 IC chips each implemented as a semiconductor integrated circuit. The IC chips are units of integration implementing the circuit blocks
112
,
113
,
115
,
116
and so on. If the radio-communication system for processing transmitted and received signals comprises a plurality of IC chips, the number of components rises, inevitably increasing an area for mounting the components. For a portable electronic device such as a hand phone, however, a small size and low power consumption are mandatory requirements. Thus, reduction of the component count is a technological challenge of importance.
In order to reduce the number of components such as ICs composing the radio-communication system of a hand phone, inventors of the present invention developed an LSI allowing some of several circuit blocks shown in
FIG. 11
to be integrated into a single semiconductor chip.
FIG. 12
is a diagram showing a layout of circuit blocks initially considered to be put in the LSI. Circuit blocks of
FIG. 12
identical with those shown in
FIG. 11
are denoted by the same reference numerals as the latter. A comparison of
FIG. 11
with
FIG. 12
clearly indicates that circuit blocks shown in
FIG. 12
are merely laid out along flows of received and transmitted signals as is the case with those shown in FIG.
11
.
By simply arranging the circuit blocks into a layout on a semiconductor chip as shown in
FIG. 12
, however, a result of an interference-wave test clearly indicated a deteriorating CN (component to noise) ratio. To put it concretely, the result of the te
Hori Kazuaki
Kasa Nobuhiro
Tashiro Yoshiyasu
Callahan Timothy P.
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
Nguyen Linh
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