Antennas with Non-Foster Matching Networks phần 4 docx

P1: RVM

MOBK060-01 MOBK060-Aberle.cls January 19, 2007 17:23

26 ANTENNAS WITH NON-FOSTER MATCHING NETWORKS

2.09 V

-456 uV -

-193 uV

+

-2.05 mV

-5 V

V￾5 V

V+

5 V

V+

-5 V

V￾2.09 nA R

R1

R=1 GOhm

1.53 mA

V_DC

SRC3

Vdc=-5 V

-1.56 mA

V_DC

SRC4

Vdc=5 V

Port

P2

Num=2

0 A

C

C8

C=0.1 uF

0 A

C

C7

C=0.1 uF

0 A

C

C9

C=0.1 uF

P ort

P 3

Num=3

P ort

P 1

Num=1

-2.09 nA

-3.57 uA

-3.33 uA

13.8 uA

1.56 mA

-1.53 mA

opa690

OP A1

FIGURE 26: Schematic of OPA690 for simulation in Agilent ADS obtained by using the SPICE model

and the data sheet for the device provided by TI

performance of several of these NIC circuits. Unfortunately, successful simulation of an NIC

circuit has not always led us to a successful physical implementation. One reason for this is that

all NIC circuits are only conditionally stable—that is certain auxiliary conditions must be met

for the circuit to be stable. In this section we will review our progress in physically realizing

NIC circuits for use in active non-Foster matching networks. The reader should be aware that

this topic is one for which a great deal of work remains to be done. It is this author’s opinion

that the major advances in this area will be made by analog circuit designers who have been

convinced by antenna engineers of the rewards to be reaped in pursuing the development of

high frequency NICs.

NIC ZL

Rin

Signal

Generator

Vin Vneg

Iin

-ZL

Vg

Rg

Zin

FIGURE 27: Circuit for evaluating the performance of a grounded negative impedance