CHQ1210J200151MQT - Cal-Chip Electronics

High Frequency Measurement and

Performance of High ‘Q’ Multilayer

Ceramic Capacitors

Introduction

Capacitors used in High Frequency applications are generally

used in two particular circuit applications:

• As a DC block providing an AC coupling path between other

components.

• As a shunt path to ground for AC voltages thus providing a

decoupling path.

At very high frequencies much more capacitor design data is

needed by a circuit designer. As well as the normal data relating

to Capacitance and Tan δ, ‘Q’ and E.S.R. are required. If

RF/Microwave Circuit Simulation aids are being used, then the

designer will require information relating to the 1 Port and 2 Port

parameters, the ‘S’ parameters denoted by S11, S21, S12, S22.

The measurement problem becomes complex because the

resultant measurements should properly describe the parameters

of the multilayer capacitor but be totally uninfluenced by any test

jigs used in the measurement.

The first and extensive part of this measurement sequence

involves the calibration (otherwise known as “de-embedding’) of

all the test jigs. The information on Cal-Chip High ‘Q’ Capacitors

contained in this catalogue has been produced utilizing a Hewlett

Packard Network Analyzer - HP8753A, together with the Hewlett

Packard ‘S’ Parameter Test Set - HP85046A.

Measurement Theory

At frequencies above 30MHz, the measurements from convention-

al capacitor bridges become invalid because it is not possible to

maintain a true four-terminal connection to the capacitor under

test, hence phase errors occur and this prohibits the separation of

the resistive and reactive components which need to be measured.

In addition the ‘open’ circuits and ‘short’ circuits used to calibrate

the bridge become degraded. The ‘open’ circuits become capaci-

tive and the ‘short’ circuits become inductive, hence measurement

accuracy is destroyed. However, other measurement techniques

can be used to solve these problems. These techniques use the

behavior of electric ‘waves’ travelling along a transmission line, e.g.

a Co-Axial Cable or a Micro-Strip Line.

If the transmission line is terminated by an unknown impedance,

e.g. the capacitor under test, then a reflected wave is created

which is sent back towards the Test Signal Generator and has a

magnitude and phase angle dependent on the unknown imped-

ance. We now have two waves, travelling in opposite directions,

giving, in effect, the required four terminal connections to the

capacitor, provided only that these waves can be separated out

and independently measured.

This separation is easily possible using variations on standard

Wheatstone Bridge principles. Hence by the measurement of the

magnitudes and phases of three travelling waves, which are

called Scattering of ‘S’ waves, the capacitor parameters can be

calculated.

It should be noted that since these measurements rely on

reflected waves, any changes in physical size, or changes in char-

acteristic impedance between the measurement system and the

points to which the capacitor is connected, will create additional

and unwanted reflected waves, which will degrade the measure-

ment accuracy.

Accuracy of capacitor placement relative to the calibration plane

is also critical. For instance, measurements of a capacitor having

a ‘Q’ of approximately 3000 and thus a Tan δof 0.00035 will mean

the phase loss angle will be of the order of 0.02 or restated -89.98

of phase or further restated, real and imaginary ratios approach-

ing 1:3000.

To achieve measurement accuracy, the connections to the

capacitor under test should operate to at least one order better

than this phase angle value. In jigging or mechanical terms

1.00mm of displacement from the correct or calibration plane, rep-

resents 0.1 of phase angle, thus the phase angle errors due to the

jigging etc., should be less than 0.02mm (0.0008”). These calcu-

lations assume a dielectric constant of 1 and a frequency of

100MHz.

Measurement Techniques

Three different Measurement Jig methods have been used:

• The H.P.16091A Co-Axial Test Jig was used to determine:

Capacitance

Tan δ

‘Q’

E.S.R.

•To stimulate the DC block mode and shunt or decoupling mode,

special Micro-Strip Line Test Jigs were designed and made.

Equipment

The measurement system used comprises a HP8753A Vector

Network Analyzer, HP85046A ‘S’ Parameter Test Set and

HP16091A Test Jig together with the relevant specialist cables,

connectors and Micro-Strip Line Test Jigs.

Notes

1) The swept frequency range over which all measurements

were taken was 1MHz to 3GHz with measurements at 10MHz

increments below 1GHz, increments of 50MHz above 1 GHz.

2) For the very low capacitance values, the lowest frequencies

at which sensible data was obtained appeared to be greater than

50 MHz, the data is thus presented.

3) The curves showing the resonant points for the capacitors

have been left in as a guide to these points of resonance.

However, due to the rapid changes in all aspects of the capacitors’

parameters near to the resonant point, such measurements

should be treated with caution. Above resonance the capacitance

curves are dominated by the self-inductance of the capacitor.

Cal-Chip EElleeccttrroonniiccss,, IInnccoorrppoorraatteedd

Surface Mount Chip Capacitors: Ultra High Frequency

Features:

• High ‘Q’ Factor at high frequencies

• High RF power capabilities

• Low ESR

• High self resonant frequencies

• Excellent stability across temperature range

• Small size

L2L3

CHQ SERIES

Cal-Chip EElleeccttrroonniiccss,, IInnccoorrppoorraatteedd

Surface Mount Chip Capacitors: Ultra High Frequency

Cal-Chip Reference Q = High Q Ceramic

Capacitance Range 0.47 pF to 1nF

Capacitance Tolerance <10pF: ±0.1pF (B),

±0.25pF (C),

±0.5pF (D)

≥10pF: ±1% (F),

±2% (G),

±5% (J),

±10% (K),

±20% (M)

Operating Temperature Range -55°C to +125°C

Voltage Rating 100V, 200V 500V

Environmental Classification 55/125/56

Typical Capacitance Change

over Temperature Range 0 ±30ppm/°C

Measuring Frequency for

Measurement of Capacitance

and Dissipation Factor 1MHz

Measuring Voltage 1Vrms

Test Voltage 2.5 x nominal

voltage/5 secs

General Technical Specifications

Ordering Information

Example:

0805 J 100 0101 KQT

Type No/

Size Ref

CHQ

Chip

Size

Te r mination

Options

J = Nickel

Barrier

Voltage d.c.

100 = 100V

200 = 200V

500 = 500V

Capacitance

Tolerance Code

Dielectric Code

Q = High Q

Ceramic

Packaging

T = Tape & Reel

178mm (7”)

dia. reel

CHQ SERIES

Type

Dimensions

Length (L1)mm

inches

Width (W) mm

max inches

Thickness (H) mm

max inches

Te r minationBand

(L2& L3)mm

inches

Rated Voltage d.c.

0603

1.6±0.2

0.063±0.008

0.8±0.2

0.031±0.008

0.8

0.031

Min Max

0.1 0.4

0.004 0.015

0805

2.0±0.3

0.08±0.012

1.25±0.2

0.05±0.008

1.3

0.051

Min Max

0.25 0.75

0.01 0.03

1206

3.2±0.3

0.125±0.012

1.6±0.2

0.063±0.008

1.6

0.063

Min Max

0.25 0.75

0.01 0.03

1210

3.2±0.3

0.125±0.012

2.5±0.3

0.10±0.012

1.8

0.07

Min Max

0.25 0.75

0.01 0.03

100 100 200 100 200 500 100 200 500

Cap.

Range

0.47pf

0.56

0.68

0.82

1.0

1.2

1.5

1.8

2.2

2.7

3.3

3.9

4.7

5.6

6.8

8.2

100

120

150

180

220

270

330

390

470

560

680

820

1.0nF

Code

0R47

0R56

0R68

0R82

1R0

1R2

1R5

1R8

2R2

2R7

3R3

3R9

4R7

5R6

6R8

8R2

100

120

150

180

220

270

330

390

470

560

680

820

101

121

151

181

221

271

331

391

471

561

681

821

102

Minimum and Maximum capacitance values available